Thomas Faulds won the case after judges decided that the risk of psychological damage was not part and parcel of his job.
Mr Faulds has already sued Strathclyde Fire Board after losing his job though post-traumatic stress disorder in 1993 after 27 years service.
The social security commissioner, who hears benefits disputes, found Mr Faulds was entitled to claim benefit because he had suffered 'personal injury caused by accident' while carrying out his job.
A spokesman for Unison said the appeal judges decision would force employers to ensure staff were not unnecessarily exposed to trauma.
'Obviously the job of the emergency services is to be called to terrible scenes of suffering, but there is a duty to ensure people's health doesn't suffer. The important thing about a case like this is that it sets a precedent and acts as a warning that mechanisms have to be in place to protect staff from the effects of witnessing terrible scenes.'